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Technology

A tried and tested physico-chemical recycling procedure.

The closed-loop recycling of PS foam waste and the destruction of HBCDD, allowing the recovery of bromine, would constitute one of the key options for dealing with the growing volumes of construction PS foam waste in the coming decades. The PolyStyreneLoop project has been assessing the economic feasibility of such a process, including all project steps from collection and transportation of PS foams to the plant, its sorting and compaction, as well as a physico-chemical recycling process.

Proprietary chemical formulations, with the lowest risk potential possible for users and the environment, dissolve selectively the target polymer. This reduces the hazard, and has positive effects on the equipment cost. Finally the desired polymer precipitates when a special formulation is added, after cleaning the solution from impurities.

A physical separation by polymer dissolution.

In the process envisaged for the demonstration plant, the polymer and the chemical of concern (for PS foam waste, HBCDD) are dissolved, enabling the separation of the said chemical. By adding a second liquid, the polymer is settling out and HBCDD remains in the solvent. The solvent is then vaporised for re-use in a closed loop and HBCDD remains as a sludge on the bottom. HBCDD stays chemically unchanged and can be subsequently destroyed. The polymer can be further re-used.

The volume of solvents used is very small in relation to the treated plastic (<1%), as the process runs in a closed-circuit in which the relatively small volume of impurities are separated and concentrated. With its energy balance it performs very well in environmental impact assessment studies.

Expanded plastics like polystyrene can be collected and dissolved at their place of origin, thus achieving a higher freight density and transport cost reduction when compared to all other current collection systems. The dissolved plastic is further processed and recycled in the plant in Terneuzen.

The PolyStyreneLoop concept will run a dissolution technology, like e.g. CreaSolv®; it will be able to recycle construction PS foam waste and to destruct HBCDD, while recovering the bromine in line with the new POP regulations stemming from the Basel Convention.

The CreaSolv® Technology is a development of the Fraunhofer Institute in co-operation with the CreaCycle GmbH. CreaSolv® is a registered trademark of CreaCycle GmbH.